There's been a few cases recently where I found an interesting article to submit here and was unable to submit it. The site appears to accept the article, but the story remains invisible to everyone and to me appears to have no comment box. I've verified that this happens when other people submit those URLs. Here are a couple of examples of apparently legitimate, genuinely interesting articles being blocked:
I'm not arguing that those sites necessarily need to be unblocked. Perhaps, on the whole, the content from these sites is not useful enough, or too much gets submitted, or someone spammed one of these sites here, or any number of other reasons.
However, in the interest of transparency (which this article suggested is an important component of a successful community culture : http://www.paulgraham.com/hackernews.html ) I think that the list of banned sites, along with the reason why they're banned, should be made public.
Or, if there's a good reason why it shouldn't be public, then I would love to know it.